Deputy County Executive Justin Mates joined the County Manager’s Office in 2019. Justin first joined the County in 2012 as an attorney in the County Counsel’s (now County Attorney's) Office, where he represented a number of County departments, agencies, and partners on projects and programs in areas such as affordable housing, revenue and finance, sea-level rise resiliency, and transportation. In 2018, he served for nearly a year as the County’s interim real property manager, during which he oversaw all transactions and strategy for the County’s real estate interests. Prior to joining the County, he worked for an international development nonprofit and as an attorney in private practice.

Justin holds a bachelor’s degree in political science from Stanford University and a juris doctorate from Harvard Law School. He lives in San Mateo County with his wife and three children.

Department Assignments

Agriculture, Weights & Measures; Community Affairs; Public Works; First 5; Information Services Department; LAFCo; Libraries; Sustainability; Parks; Planning & Building; Real Property; Well Being Officer